1. Field of the Invention
The present invention relates to an anti-glypican 3 antibody, a cell growth inhibitor and an anticancer agent containing the antibody as an active ingredient.
2. Description of Related Art
Glypican 3 (GPC3) is one of the glypican family of heparan sulfate proteoglycans that are present on cell surfaces. It is suggested that GPC3 may be involved in cell division in development or cancer cell growth, however, its function has not been well elucidated yet.
It has been found that a certain type of antibody binding to GPC3 has a cell growth-inhibiting activity via an antibody-dependent cell-mediated cytotoxicity (ADCC) activity and a complement-dependent cytotoxicity (CDC) activity (International Patent Application WO 2003/000883). In addition, it has been suggested that GPC3 is cleaved in vivo and secreted into blood as a secreted form of GPC3, and the diagnosis of cancers may be possible by using an antibody capable of detecting the secreted form of GPC3 (International Patent Applications WO 2004/022739, WO 03/100429 and WO 2004/018667).
When developing an anticancer agent based on the cytotoxicity activity of an antibody, it is preferred that the antibody to be used has high ADCC activity or CDC activity. Accordingly, an anti-GPC3 antibody having a high cytotoxicity activity has been desired as an antibody recognizing GPC3.
An object of the present invention is to provide an anti-GPC3 antibody having a higher ADCC activity and CDC activity compared with those of a conventional antibody.